5.  The applicants were born in 1944 and 1945 respectively and live in the village of Dospey.
6.  The applicants are the parents of Angel Georgiev, who died on 26 December 1993, aged 23.
7.  In the criminal proceedings related to Angel Georgiev’s death, the national courts established the relevant facts as follows.
8.  On the evening of 25 December 1993 the applicants’ son was with friends of his in a bar in the town of Samokov. At some point an argument and a fight erupted between Angel and his friends and another group, one of whom was K.S. O.V., who was working as a security guard in the bar, attempted to separate the two groups, but was himself beaten up. The two groups went on to another bar, where there was another argument. The two groups then left.
9.  O.V. gathered friends of his, who took several cars and started searching the streets for the people who had beaten him up. They found Angel Georgiev’s group, walking home. O.V. and his friend B.G. were among the first to get out of the cars. O.V. went first for Angel Georgiev’s brother, who ran away, while at the same time B.G. hit Angel Georgiev with a wooden plank. Angel fell to the ground, but managed to stand up again, and was then attacked by O.V. The two of them struggled briefly, until O.V. drew back, saying that Angel had stabbed him in the abdomen. O.V. was then taken by his friends to a hospital, and Angel ran away.
10.  During that time K.S. and his friends had also been driving around the area. They heard people fighting in the distance and approached them. They saw somebody, who turned out to be Angel Georgiev, lying on the ground. First they kicked him repeatedly, but then became aware that he had been seriously wounded. They fled the scene, leaving him lying on the ground.
11.  Angel Georgiev’s body was found by his brother the following morning, 26 December 1993, at the place where he had been left by K.S. and his friends, namely about 200 metres away from the scene of the struggle with O.V. Next to the body lay the pocket knife with which Angel had stabbed O.V. as found later by the investigation and the national courts.
There were shoeprints and car-tyre tracks around the body.
12.  A post-mortem report showed that the applicants’ son had been lethally stabbed in the back. The blow had been administered while he had been standing, with considerable force. For some time thereafter, he had still been capable of moving and even running. He had died as a result of a hemorrhage in the chest cavity. There were other wounds and bruises on his face and head, which were unrelated to the cause of death.
13.  Criminal proceedings in connection with Angel Georgiev’s murder were opened on 26 December 1993.
14.  The place where his body had been found was inspected on the same day.
15.  In the weeks that followed many of the participants in the events were interviewed by the investigating authorities. Some of them were interviewed again in 1997, after the prosecutor supervising the case had found that the relevant circumstances had not been adequately established.
16.  On 28 December 1993 and 9 February 1994 respectively, the investigator in charge of the case charged K.S. and O.V. with Angel’s murder. K.S. was remanded in custody from 28 December 1993 to 2 March 1994, and O.V. from 9 February to 8 March 1994. The two accused were questioned on numerous occasions. K.S. denied having killed Angel Georgiev. O.V. initially confessed to having stabbed the victim but then withdrew his confession, explaining that K.S. had asked him to make it. On 13 May 1996 the investigator organised a confrontation between the two accused in order to clarify their versions of the events.
17.  The investigator in charge of the case commissioned several reports by medical and other experts.
18.  On 24 June 1994 the applicants were presented with the evidence collected thus far and given a chance to comment on it. On several subsequent occasions they were again given an opportunity to acquaint themselves with the case file and to comment.
19.  In June and December 1994, January and November 1996, and then in December 1997 the investigator in charge of the case sent the case file to the prosecution, proposing either to stay the proceedings or to indict K.S. and O.V. However, each time the supervising prosecutor remitted the case, considering that further evidence needed to be collected, or that the procedural rights of the two accused had not been respected. In particular, on 9 December 1996 the prosecutor ordered the detailed questioning of the participants in the altercation, with a view to establishing their position, actions and observations during the incident. The prosecutor also instructed the investigating authorities to identify the owner of the knife discovered in the proximity of the victim’s body and which knife had been apparently used by the victim to stab O.V. This latter instruction was subsequently repeated in another prosecutor’s ruling of 29 January 1998. In 1996 the prosecutor replaced the investigator dealing with the case.
20.  Once the preliminary investigation was completed in 1999, the prosecutor indicted K.S. and O.V. and they were brought before a court.
21.  At a court hearing on 9 June 1999 the applicants joined the proceedings as private prosecutors and civil claimants.
22.  In a judgment of 5 June 2000 the Sofia Regional Court found O.V. guilty of murdering the applicants’ son, sentenced him to thirteen and a half years’ imprisonment and ordered him to pay damages to the applicants. On the grounds, among others, that the victim’s blood had been found on O.V.’s clothes, it concluded that O.V. had stabbed him in the back during the short struggle between the two of them. Moreover, B.G. had seen a knife in O.V.’s hands at an earlier point, and it had not been shown that any of the other participants in the fight had had a knife.
23.  The Regional Court considered that there was no evidence that K.S. had in any way caused Angel Georgiev’s death, and accordingly acquitted him.
24.  O.V. lodged an appeal against that judgment. The decision to acquit K.S. entered into force, as it had not been challenged by the prosecution or the applicants.
25.  On 30 April 2002 the Sofia Court of Appeal quashed the lower court’s judgment, finding that O.V.’s conviction had been impermissibly based on assumptions. It acquitted him and disallowed the applicants’ civil claim, noting, in particular, that it had not been established that when he had attacked Angel Georgiev, O.V. had been in possession of the knife which had allegedly been seen earlier. It was also significant that the knife used to stab Angel Georgiev had never been found. In addition, none of the eyewitnesses to O.V.’s struggle with Angel Georgiev had seen him stab the victim. As O.V. had himself been stabbed by Angel, the struggle between the two of them had been brief. O.V. had then left the scene and had been taken to hospital. It was thus possible that the applicants’ son had been stabbed by someone else after O.V.’s departure, or even before that, as the post-mortem and other medical reports showed that after having been fatally stabbed, Angel had still been capable of moving and participating in the fight. The victim’s blood had also been discovered on K.S.’s clothes, and it might have been discovered on the clothes of other participants in the fight, had they been seized and inspected during the initial investigation. Accordingly, there could be different plausible versions of the facts preceding Angel Georgiev’s death, which meant that O.V.’s guilt had not been proved beyond reasonable doubt.
26.  Following an appeal by the prosecution, on 6 February 2003 the Supreme Court of Cassation quashed the above-mentioned judgment and remitted the case, finding that the lower court had not duly taken into account the incriminating evidence, in particular the presence of the victim’s blood on the accused’s clothes.
27.  In a judgment of 8 April 2003 the Sofia Court of Appeal once again acquitted O.V. and dismissed the applicants’ civil claim. It again found that it had not been established beyond reasonable doubt that the accused had fatally stabbed the applicants’ son. It pointed out that it had not been shown that during the struggle with Angel, O.V. had had a knife, as none of the eyewitnesses had seen him brandish, pick up or use one. If he had had a knife at that time, it was unclear what had happened to it after the stabbing. As to the blood on O.V.’s clothes, it could be explained by the fact that B.G. had already hit Angel in the face with a wooden plank, which had provoked bleeding. One of the other participants in the fight could have stabbed the applicants’ son. It was significant in that regard that when K.S. and his friends arrived at the scene, the fight was still going on. Lastly, the Court of Appeal noted that the prosecution had also faced difficulties in establishing who had stabbed the applicants’ son, and had thus indicted two persons, O.V. and K.S., leaving to the courts the “choice” as to which of the two was guilty.
28.  The applicants and the prosecution appealed against the above‑mentioned judgment. On 18 March 2004 the Supreme Court of Cassation quashed it and remitted the case. It found this time that there had been breaches of the procedural rules.
29.  In a judgment of 7 April 2005 the Sofia Court of Appeal acquitted O.V. once again and dismissed the applicants’ civil claim. It found that there was no conclusive evidence that the accused had committed the offence.
30.  The applicants and the prosecution again lodged appeals on points of law.
31.  In a judgment of 18 May 2006 the Supreme Court of Cassation quashed the lower court’s judgment and remitted the case. It considered again that the Court of Appeal had not sufficiently accounted for the fact that there had been traces of the victim’s blood on the accused’s clothes and that B.G. had stated that before the fight he had seen the accused holding a knife.
32.  In a judgment of 11 January 2007 the Sofia Court of Appeal acquitted O.V., finding that in view of the evidence collected, more than one conclusion could be drawn as to who had fatally stabbed the applicants’ son. The Court of Appeal noted that the victim had apparently already been bleeding when he had exchanged blows with O.V., because B.G. had already hit him with a plank, which could explain why O.V.’s clothes were smeared with the victim’s blood. In addition, none of the witnesses had seen O.V. stab the victim and the knife used for the murder had never been found; moreover, B.G.’s statement that he had seen O.V. holding a knife was not convincing, as it contradicted his other statements. It was thus possible that someone else had stabbed the applicants’ son; no definite conclusion could be drawn in that regard, since during the preliminary investigation it had not been established whether anyone else had had a knife, the clothes of the other people involved in the fight had not been examined, and the investigating authorities had not carried out a more extensive search of the area where the fight had taken place in order to locate the knife which had caused the lethal wound. Lastly, it appeared that even at the stage of the preliminary investigation it had been difficult to establish who had dealt the fatal blow to Angel Georgiev; that is why the prosecution had indicted two persons, even though it had been clear that the young man had died as a result of a single stab in the back.
33.  The applicants and the prosecution lodged appeals on points of law against that judgment.
34.  In a final judgment of 28 June 2007 the Supreme Court of Cassation upheld the lower court’s judgment, endorsing its reasoning.